An early fingerprint recognition system is provided with a ring. A radio-frequency (RF) signal is applied on the ring and detected by a sensor, and the radio-frequency signal may be distort due to applying of a fingerprint. If a thickness of encapsulation needs to be increased, the amplitude of the radio-frequency signal also needs to be increased. However, the increase of the amplitude of the radio-frequency signal may make a user feel uncomfortable on the finger. Therefore, a technical solution in the conventional technology is by grounding the ring and improving a voltage of a sensor chip, thereby, alleviating the problem of poor tactile experience of a finger and achieving the same technical effect with applying a radio-frequency signal on a ring.
In order to achieve the above object, some circuits in a sensor chip need to operate at two different ground potentials, such as a first ground voltage GND and a second ground voltage NGND. In most cases, the first ground voltage GND is equal to the second ground voltage NGND. However, the second ground voltage NGND is increased when detecting a fingerprint, and the increase of the second ground voltage NGND will cause a high voltage potential to increase correspondingly.
When the sensor chip is connected to other circuits to transmit a signal, increasing of the voltages as described above tends to cause a breakdown of the connected circuits.